Michelle Johnson has looked back at her Iowa upbringing as a 'north star' to guide her through obstacles. (AP)

DES MOINES, IOWA — When Lt. Gen. Michelle Johnson was a child, she would climb up onto her parents’ hog house with her German shepherd and look out at the horizon. It was one of her favorite afternoon activities as a rural latchkey kid left to her own devices after school.

“You could see the horizon out there in the Midwest, and you could see the curvature of the earth, just about, and what a big, big world it is,” said Johnson, who in August 2013 became the first female superintendent of the U.S. Air Force Academy in Colorado Springs, Colo.

“I just wondered, ‘Would it be possible to get out in that big, big world and see what happened?’”

Johnson, 55, is still discovering the possibilities. After graduating from high school in 1977, she entered the Air Force Academy as a member of only the second class to enroll women to train for a career as an officer. In her senior year, she was the first woman to serve as cadet wing commander, the most senior rank attainable at the four-year institution. She graduated from the academy in 1981, a Rhodes Scholar.

Thirty-two years later, after a distinguished career as an Air Force aide to two presidents, a Pentagon director for cyberspace policy and an intelligence chief at NATO in Brussels, she returned to the academy to take charge.

She takes the helm at a challenging time:

■ Sexual assault in the military, which Johnson has vowed to tackle in her tenure, is a high-profile issue currently being debated in Congress.

■ The 2011 repeal of “Don’t Ask, Don’t Tell,” the service ban on gays and lesbians in the military, has welcomed an openly gay cohort of students, underlining a need to strengthen diversity in the academy.

■ And Department of Defense budget constraints have forced Johnson to identify what makes the service academy worth the cost to taxpayers.

Her colleagues say she is up to the task. “Michelle Johnson was simply built for this job,” said Gen. Mark A. Welsh III, the Air Force chief of staff. “She’s an incredibly accomplished officer and commander and serves as a leading proponent for change and modernization within our Air Force. ... She clearly understands the benefits of respect and inclusion, and the strength of diversity, exactly the type of leader we want here.”

On the personal side, Johnson has had to face challenges with her health after a diagnosis of multiple sclerosis a decade ago. She thinks of herself as fortunate: She has few symptoms, and none that affects her work.

Whether navigating the barriers she broke early in her career or the challenges she faces today, Johnson has looked back at her Iowa upbringing as a “north star” to guide her through those obstacles.

“To have a Polaris to follow of your foundation of values and doing the right thing, it’s very grounding when there’s turbulence around you,” said the pilot who has logged more than 3,600 flight hours.

She credits her parents, who farmed in Iowa as the Great Depression ended, for instilling in her an “honor code” -- don’t lie, look out for others, always give your best. She heeded that code as a teen, as a state champion hurdle relay runner and basketball star.

Her friends say she held herself to the highest of standards, whether on the track or the court, or helping out at her parents’ burger stand, the Zesto, which became a hangout in mid-1970s Spencer.

High school friend Julie Williams remembers Johnson giving her a pep talk after she got knocked down at a track meet.

“She was always the first one to lift people up,” Williams said, “and I think she is still doing that now through the military.”

Blazing a trail was hardly easy. Johnson remembers how classmates and even faculty made her feel when she first entered the academy, in a class that was only 12 percent female.

“It was a bit of a shock to be a numerical minority,” she said. “When I came, the atmosphere was overtly, from many people, ‘We don’t want you here.’”

Today, she says, the culture is different.

“There is more of a need to respect boundaries, because people are open with each other, but bring these different ideas they get from their upbringings of who should be in charge, who is in power, who belongs here.”

And while women have made strides in the ranks, 180 openly gay, lesbian, bisexual and questioning cadets at the academy are facing some of the same issues Johnson did when she started.

Johnson says it requires overcoming peer pressure and maintaining a commitment to service above personal interests for the academy’s 4,000 students to accept one another fully. But “that’s a tough one to put into practice on a weekend night at a party for a 20-year-old, I think.”

A mother of 11-year-old twins, Johnson said communicating across the generation gap with millennials is one of the challenges of her position. But that didn’t stop her from raising the issue of sexual assault and sexual harassment in the military in her first talk to new cadets last fall.

“Sexual assault is a crime,” she told students. “When you cross those boundaries, there’s a human cost to that. There’s a lifetime human cost on both parties, and that’s what we need to be aware of.”

Her words echo a larger conversation about sexual assault in the military at a time of increased scrutiny.

An estimated 26,000 instances of unwanted sexual contact occurred among troops in 2012, according to a Pentagon report — a 35 percent increase in reported incidents since 2010. Last year, the officer in charge of the Air Force’s Sexual Assault Prevention and Response Office was arrested on charges of groping a woman in a parking lot near the Pentagon. Last week, the Army disqualified 588 soldiers from “positions of trust,” including counselors, recruiters and drill sergeants, after an investigation into past infractions that included sexual assault.

Bills that would overhaul the way sexual assault cases are handled are floating in Congress. Sen. Kirsten Gillibrand, D-N.Y., is close to collecting the 60 votes needed to pass her proposal, which would remove prosecution decisions from the chain of command.

In a survey about sexual assault issues at the U.S. military’s three service academies, the Air Force Academy reported 45 instances of sexual assault during the 2012-13 academic year.

In response, Johnson adopted a “zero tolerance” policy at the academy, hiring two victim advocates and expanding the sexual assault program to provide 24-hour support for victims. She has also created a new position to address culture and diversity at the academy.

Maj. Gen. Margaret Woodward, who retired in January as the leader of the Air Force’s Sexual Assault Prevention and Response office, credited Johnson with taking a broad approach to the issue.

“I think too often, people just address the symptoms,” Woodward said. “She’s really getting at the heart of what will change the issue -- dignity and respect and really developing a professional core.”

“It’s a breath of fresh air to hear of someone with a distinguished rank working on this problem,” Grassley said. “The culture of our military has to change so its members have each other’s backs and are able to stop worrying about the enemy within. Starting at the early part of military service makes sense to establish appropriate conduct from the beginning.”

Johnson says her mission as superintendent comes from the Air Force ethos of “let’s go over, not through,” advice she has relied on through the “soul-searching” the institution is going through, especially now as it faces proposed cuts in military spending.

“There’s another way to solve this,” she said. “We can bring something else to the fight. There’s a different way of thinking.”

Today, a quarter of the cadets at the academy are women. When Johnson talks to them about her experience three decades ago, she said “they can’t imagine things were different than they are now, or that there were less choices.”

She says there is still “work to do” for women to gain true equality. Until then, a lesson Johnson learned as a trailblazing cadet remains relevant.

“One of the advantages of being in a fairly meritocratic system, and then going into operations, is the airplanes don’t care where you came from,” Johnson said. “As long as you make the right inputs and do the right things, you can earn respect and trust from others.